Electromagnetic relay



Patented Jan. 4, 1949 ELECTROMAGNETIC RELAY Ernest Alfred Bryan, Bexley; England, assignor to Siemens Brothers & Co. Limited, London, England, a British company Application February 5, 1945, Serial No. 576,283

- In Great Britain October 8, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires October 8, 1963 This invention relates to electromagnetic relays and more particularly to relays of the kind adapted for high speedoperation wherein the armature is secured to a fiat spring which is tensioned to hold a part of the armature against a part of the relay core leaving a small air-gap between the armature and a pole-face of the relay core. A relay of this character is described in specification of Patent No. 1,992,610 to Ernest J. Gachet.

The main features of the relay of the present invention resides in the manner in which the tension is applied to the flat spring.

In the present invention it is arranged that tension is applied to the said spring by means of a member integral with it or suitably attached thereto and extending outwardly therefrom and has tension applied to it at or near its end. The member may extend backwardly towards or even beyond the place of fixture of the spring. For adjusting the tension in the member its end may be slotted to engage an adjusting screw screwing into the framework of the relay.

Conveniently the armature spring may be constructed as a three pronged fork, the two outer prongs being fixed at their ends to secure the spring whilst the middle prong is employed as the said member. The other end of the spring consisting of a single extension, carries the armature, and may be a contact point for making contact with fixed contacts, and may be channelled to impart rigidity thereto.

The fixed contact or contacts may be provided at the ends of cantilever members of a thickness such as will provide adequate rigidity yet avoid contact bounce, having their fixed ends secured in assembly with, but insulated from, the aforesaid outer prongs, and the extremities of these members are preferably supported against vibration, and for adjustment, against insulating adjustable stops engaging the framework of the relay.

The relay is provided with a backplate by which it is adapted to be secured to a rigid mounting and which also supports a cover covering the components of the relay. The joint between the cover and the backplate may be sealed to prevent the ingress of moisture. One method by which this may be accomplished is to form the backplate of two plates of rigid material between which is compressed a body of compressible moisture-impervious material, such as rubber, the said material being adapted tightly to fit within the cover when the latter is placed in position and effect a seal. In this arrangement, where 1 Claim. (Cl. 175-336) wiring terminals pass through the backplate it is convenient to clamp these in position by providing bulbous portions thereon, which portions are trapped between the said material and one of the rigid plates.

In an alternative arrangement to the above for sealing the cover, the backplate may have moulded thereinto a metal edging over which the mouth of the cover is adapted to slide, the cover being of metal, or of a plastic having a metal mouth moulded thereinto, the joint being sealed such as by soldering the mouth of the cover to the edging,

To permit easy inspection oi" the contacts 01' the relays, a window may be provided in the cover adjacent the contacts. V

One manner in which the present invention may be carried into effect is illustrated by way of example in the accompanying drawings, the arrangements of which are described in the followin description.

In the drawings Fig. 1 shows a side elevation of a relay with the side of the cover removed to disclose the interior arrangements, the backplate being shown in section along a line marked X in Fig. 2 which gives a rear view of the relay, that is, the left-hand end of the relay shown in Fig. 1. Fig. 3 shows a plan view of the relay, the top of the cover being removed, and Fig. 4 shows a sectional view of the relay looking towards the right from line Y in Fig. 3. Fig. 5 shows a method diilerent from that shown in Fig. 1 for mounting and sealing the cover, and also shows how a window may be provided in the cover through which the contacts may be viewed, and Fig. 6 shows a rear view of Fig. 5.

Referring to Figs. 1 to 4 the various components of the relay electro-mechanism are mounted on a framework bent up from strip or bar metal, such as iron, to form a horizontal yoke portion I having at its left hand end a vertically upstanding portion or limb 2, shown in section, which itself has its end bent inwards as indicated at 3 to form an inturned bracket lying over and parallel with the yoke I. At the right-hand end of the yoke portion I is a vertically upstanding portion or limb 4 having its end bent outwards at right angles to form an outwardly projecting bracket as indicated at 5. Thus the framework can be described as being substantially U-shaped having the end of one of its limbs (2) bent inwards (3) over and parallel with the yoke (I), whilst the end of the other limb (4) is bent outwards (5) away from and parallel with the yoke.

Secured to the yoke l of the framework between the limbs 2 and 4 is an electromagnet assembly. This assembly comprises a U-shaped core 6 having about each limb an energising winding 1, the core being secured yoke to yoke with the frame by screws (not shown) so that the electromagnetic assembly lies co-planar with the frame.

The bracket 3 supports the spring contact assembly. This assembly is shown as a change over contact set comprising two outersprings 8 and 9 and an inner moving spring II) which normally, that is, when the relay is not energised, makes contact with the upper spring 8, but breaks this contact and makes contact with the lower spring 9 when the relay is energised.

The springs 8 and 9 are both substantially L-shaped in form and are clamped by their shorter horizontal limbs I I, in reverse manner to each other, to the bracket 3 by means of bolts I 2, there being insulating washers I3 between the springs and insulating collars passing through them to insulate them from one another and from the framework. The ends of the longer vertical limbs ll of the springs are formed to project inwardly as indicated at I and have contact pieces riveted into these inward projections.

The moving spring III is in the form of a threepronged fork and consists of a single extension I8 which branches into two outer prongs '1 and I8 and a middle prong IS. The ends of the two outer prongs I1 and I8 are suitably formed for clamping in the spring assembly to the bracket 8 whilst the middle limb extends beyond the place of fixing of the former limbs and has its end bifurcated to engage the underside of the head of an adjusting screw 2| engaging the bracket 3 and being locked by a locking nut 22.

The single extension I8 may have portions of its edges bent up for re-inforcement, and has secured to its underside such as by riveting or spot welding, a soft iron armature 23 disposed so as to be situated above the pole-ends of the core of the electromagnet. An aperture may be provided situated between the armature and the extremity of the extension to lessen windage. The middle prong I 9 engages beneath the head of the adjusting screw 2|, and it will be seen that, by reason of the tension in the middle prong ,which will exert downward pressure at the place where the three prongs are joined to the single extension I 8, the left-hand end of the armature will, be forced down onto the left-hand pole-face of the core of the electromagnet and by a pivoting action about this pole face the other end of the armature will be lifted away from the other pole-face and at the same time the end of the extension I8 will be lifted to bringa contact point riveted thereinto into contact with the contact point of the spring 8. When the electromagnet is energised the right-hand end of the armature is attracted towards its adjacent pole-face and the armature pivots around the left-hand pole face causing the end of the extension I8 to move downwards leaving the spring 8 and making contact with the spring 9. The tension in the prong I9 is simply adjusted by turning the screw 2I in the appropriate direction and locking the screw by its lock nut 22. v

The ends of the springs 8 and 9 are adjustably supported against vibration and bounce by being tensioned to rest on stop pillars 24 of insulating material (see particularly Fig. 4) attached to adlusting screws which in turn are screwed into and locked to the bracket 5 outstanding from the vertical limb 4 of the framework. Adjustment d is made by screwing the pillars 24 up or down by means of the adjusting screws.

There may be provided in front of the contacts a guard 26 of any suitable but preferably insulating material secured to the vertical limb d of the framework to prevent inadvertent mechanical interference with the contacts and to serve as a guide and limiting stop for the cover later referred to.

The framework is secured by its left-hand vertical limb 2 to a backplate which comprises three parts, namely an inner plate 28 of insulating material, an intermediate cup shaped moulding 21 of compressible material such as rubber with its dished partturned outwards, and an outer moulded plate 28 of insulating material which fits into the recess of the intermediate part 21, and these are screwed as a pack to the limb 2, the part 21 being compressed between the parts 28 and 28. These parts all have holes therein for permitting the passage therethrough of wiring terminals 23 and these terminals are provided with bulbous portions 30 which on clamping up the pack compress the part 21 and are thus held firmly. The outer part 28 on its interior may be countersunk adjacent each hole to permit the deformation of the part 21 thereinto by the bulbous portions 30 on the pack being clamped up, and on its exterior may have bosses extending from each hole, as shown, which serve the dual purpose of giving additional support for the terminals and also increasing the electrical leakage path. The wiring from the terminals to the windings of the electromagnet and the spring I8 is indicated generally by 3 I.

The cover 32 for the relay in Figs. 1, 2 and 3 is shown as an elongated parallelepiped metal casing having one end open and expanded. This cover is slipped over the relay mechanism so that its expanded end passes over the backplate, and

its end is turned down over the exterior surface of the backplate. Thus by providing that the intermediate part 21 is sufiiciently large or expanded intimately to bear on the cover a fluid and vapour tight sealing of the joint can be obtained. Prior to turning over the edge of the cover and sealing of the joint the relay may be heated to drive of? moisture. As an additional protection against moisture being deposited upon the component parts of the mechanism of the relay a small quantity of a dessicating agent, such as silica gel, may be provided in the cover accommodated in a suitable cell or attached by suitable varnish.

An alternative construction of backplate and method of sealing the cover is illustrated in Figs. 5 and 6. In this method the backplate consists of a moulding of insulating material 33 into which are moulded the wiring'terminals 29 and also a metal edging 34. The cover 32 also of metal, slips over and has its edge soldered to the metal edging 34 as indicated at 35, the relay preferably being heated prior to the soldering as and for the purv pose aforementioned. Instead of solder a thermosetting cement may be used and this also applies to the arrangement of Fig. 1 for sealing the edge of the cover to the part 28 if necessary. This also applies where the cover and backplate are entirely of plastic material.

The cover 32 in Fig. 5 is shown provided with a window through which the contacts may be observed. This window is shown as a piece of transparent material 36 such as glass or a transparent ture in the casing, by means of a sheet metal bushing 38 secured to the casing such as by soldering or welding and surrounding the aperture and which has its edge turned over to effect the clamping. The guard 25 will have therein an aperture corresponding in position to the window.

I claim:

In an electromagnetic relay, a U-shaped core having two pole faces, a spring having an armature portion and right and left branches extending therefrom, means located at a distance from said armature portion for fixedly supporting the outer ends of said right and left branches to position said armature portion above and clear of both said pole faces, said right and left branches sufliciently long to permit ready flexing of said right and left branches between said supporting means and said armature portion, an elongated armature secured to said armature portion adja cent to but clear of both said pole faces, a third branch intermediate said right and left branches extending from said armature portion beyond said supporting means of said right and left branches, means engaging the outer end of said' intermediate branch for tensioning said intermediate branch to downwardly flex said right and left branches, said downwardly flexed right and 6 left branches cooperating with said tensioned intermediate branch for exerting pressure downwardly on said armature portion in the immediate area where said right, left and intermediate branches merge with said armature portion, thereby to force one end of said armature down on and in contact with one of said pole faces, said contacting of said one end of said armature with said one pole face pivoting said armature with respect to said other pole face thereby to provide a small air gap between the other end of said armature and said other pole face.

ERNEST ALFRED BRYAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,140,433 Ames May 25, 1915 1,207,736 Forsberg Dec, 12, 1916 1,508,386 Galamb Sept, 16, 1924 1,867,099 Roe July 12, 1932 1,944,661 Kalwitz Jan. 23, 1934 1,992,610 Gachet Feb. 26, 1935 2,366,784 Hawley Jan. 9, 1945 

